This disclosure generally relates to polymeric sheets, more specifically to polymeric sheets for light emitting diode (LED) light cover applications.
Hiding power and light transmission are two important parameters for optical performance of a sheet for LED light cover applications. Although light diffusing particles (diffuser) in the sheet may improve the hiding power to some extent, the improvement is limited, typically at the expense of light transmission. Specifically, to achieve a reasonable hiding power performance, a certain amount of diffuser loading is required. The required diffuser loading to attain a desired hiding power increases as the sheet thickness decreases. For sheets having a thickness below 0.5 mm, the required diffuser loading can reach as high as 0.5 wt % for silicone based diffuser and 1 wt % for polymethyl methacrylate (PMMA) based diffuser, which makes it very difficult to obtain balanced hiding power and light transmission economically.
Accordingly, a continual need exists in the art for improved polymeric sheets, especially thin polymeric sheets having good hiding power and light transmission, which are suitable for LED light cover applications.